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Class: ActiveRecord::Reflection::ThroughReflection

Do not use. This class is for internal use only.
Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, AbstractReflection
Instance Chain:
self, AbstractReflection
Inherits: ActiveRecord::Reflection::AbstractReflection
Defined in: activerecord/lib/active_record/reflection.rb

Overview

Holds all the metadata about a :through association as it was specified in the Active Record class.

Class Method Summary

AbstractReflection - Inherited

.new

Instance Attribute Summary

AbstractReflection - Inherited

#counter_must_be_updated_by_has_many?,
#has_active_cached_counter?

Returns whether this association has a counter cache and its column values were backfilled (and so it is used internally by methods like size/any?/etc).
#has_cached_counter?

Returns whether this association has a counter cache.
#inverse_updates_counter_cache?

Alias for AbstractReflection#inverse_which_updates_counter_cache.
#inverse_updates_counter_in_memory?, #strict_loading?, #through_reflection?

Instance Method Summary

AbstractReflection - Inherited

#alias_candidate,
#build_association

Returns a new, unsaved instance of the associated class.
#build_scope, #chain, #check_validity_of_inverse!,
#class_name

Returns the class name for the macro.
#constraints, #counter_cache_column, #inverse_of,
#inverse_which_updates_counter_cache

We need to avoid the following situation:
#join_scope, #join_scopes, #klass_join_scope,
#scopes

Returns a list of scopes that should be applied for this ::ActiveRecord::Reflection object when querying the database.
#strict_loading_violation_message, #table_name,
#actual_source_reflection

FIXME: this is a horrible name.
#ensure_option_not_given_as_class!, #predicate_builder, #primary_key

Constructor Details

.new(delegate_reflection) ⇒ ThroughReflection

[ GitHub ] 

  


# File 'activerecord/lib/active_record/reflection.rb', line 968



def initialize(delegate_reflection)
  super()
  @delegate_reflection = delegate_reflection
  @klass = delegate_reflection.options[:anonymous_class]
  @source_reflection_name = delegate_reflection.options[:source]

  ensure_option_not_given_as_class!(:source_type)
end


  







Instance Attribute Details



  

    #active_record_primary_key   (readonly)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 965



delegate :foreign_key, :foreign_type, :association_foreign_key, :join_id_for, :type,
         :active_record_primary_key, :join_foreign_key, to: :source_reflection


  








  

    #association_foreign_key   (readonly)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 965



delegate :foreign_key, :foreign_type, :association_foreign_key, :join_id_for, :type,
         :active_record_primary_key, :join_foreign_key, to: :source_reflection


  








  

    #delegate_reflection   (readonly, private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1194



attr_reader :delegate_reflection


  








  

    #foreign_key   (readonly)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 965



delegate :foreign_key, :foreign_type, :association_foreign_key, :join_id_for, :type,
         :active_record_primary_key, :join_foreign_key, to: :source_reflection


  








  

    #foreign_type   (readonly)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 965



delegate :foreign_key, :foreign_type, :association_foreign_key, :join_id_for, :type,
         :active_record_primary_key, :join_foreign_key, to: :source_reflection


  








  

    #has_scope?  ⇒ Boolean  (readonly)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1059



def has_scope?
  scope || options[:source_type] ||
    source_reflection.has_scope? ||
    through_reflection.has_scope?
end


  








  

    #join_foreign_key   (readonly)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 965



delegate :foreign_key, :foreign_type, :association_foreign_key, :join_id_for, :type,
         :active_record_primary_key, :join_foreign_key, to: :source_reflection


  








  

    #join_id_for   (readonly)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 965



delegate :foreign_key, :foreign_type, :association_foreign_key, :join_id_for, :type,
         :active_record_primary_key, :join_foreign_key, to: :source_reflection


  








  

    #nested?  ⇒ Boolean  (readonly)
  



  

    

A through association is nested if there would be more than one join table


  





  


  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1066



def nested?
  source_reflection.through_reflection? || through_reflection.through_reflection?
end


  








  

    #through_reflection?  ⇒ Boolean  (readonly)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 977



def through_reflection?
  true
end


  








  

    #type   (readonly)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 965



delegate :foreign_key, :foreign_type, :association_foreign_key, :join_id_for, :type,
         :active_record_primary_key, :join_foreign_key, to: :source_reflection


  







Instance Method Details



  

    #actual_source_reflection   (protected)
  



  

    

FIXME: this is a horrible name


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1189



def actual_source_reflection # FIXME: this is a horrible name
  source_reflection.actual_source_reflection
end


  








  

    #add_as_polymorphic_through(reflection, seed)  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1180



def add_as_polymorphic_through(reflection, seed)
  collect_join_reflections(seed + [PolymorphicReflection.new(self, reflection)])
end


  








  

    #add_as_source(seed)  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1176



def add_as_source(seed)
  collect_join_reflections seed
end


  








  

    #add_as_through(seed)  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1184



def add_as_through(seed)
  collect_join_reflections(seed + [self])
end


  








  

    #association_primary_key(klass = nil)  
  



  

    

We want to use the klass from this reflection, rather than just delegate straight to the source_reflection, because the source_reflection may be polymorphic. We still need to respect the source_reflection’s :primary_key option, though.


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1073



def association_primary_key(klass = nil)
  # Get the "actual" source reflection if the immediate source reflection has a
  # source reflection itself
  if primary_key = actual_source_reflection.options[:primary_key]
    @association_primary_key ||= -primary_key.to_s
  else
    primary_key(klass || self.klass)
  end
end


  








  

    #check_validity!  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1130



def check_validity!
  if through_reflection.nil?
    raise HasManyThroughAssociationNotFoundError.new(active_record, self)
  end

  if through_reflection.polymorphic?
    if has_one?
      raise HasOneAssociationPolymorphicThroughError.new(active_record.name, self)
    else
      raise HasManyThroughAssociationPolymorphicThroughError.new(active_record.name, self)
    end
  end

  if source_reflection.nil?
    raise HasManyThroughSourceAssociationNotFoundError.new(self)
  end

  if options[:source_type] && !source_reflection.polymorphic?
    raise HasManyThroughAssociationPointlessSourceTypeError.new(active_record.name, self, source_reflection)
  end

  if source_reflection.polymorphic? && options[:source_type].nil?
    raise HasManyThroughAssociationPolymorphicSourceError.new(active_record.name, self, source_reflection)
  end

  if has_one? && through_reflection.collection?
    raise HasOneThroughCantAssociateThroughCollection.new(active_record.name, self, through_reflection)
  end

  if parent_reflection.nil?
    reflections = active_record.reflections.keys.map(&:to_sym)

    if reflections.index(through_reflection.name) > reflections.index(name)
      raise HasManyThroughOrderError.new(active_record.name, self, through_reflection)
    end
  end

  check_validity_of_inverse!
end


  








  

    #clear_association_scope_cache  
  



  

    

This is for clearing cache on the reflection. Useful for tests that need to compare SQL queries on associations.


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1045



def clear_association_scope_cache # :nodoc:
  delegate_reflection.clear_association_scope_cache
  source_reflection.clear_association_scope_cache
  through_reflection.clear_association_scope_cache
end


  








  

    #collect_join_chain  
  



  

    

Returns an array of reflections which are involved in this association. Each item in the array corresponds to a table which will be part of the query for this association.



The chain is built by recursively calling #chain on the source reflection and the through reflection. The base case for the recursion is a normal association, which just returns


self



as its #chain.





class Post < ActiveRecord::Base
  has_many :taggings
  has_many :tags, through: :taggings
end

tags_reflection = Post.reflect_on_association(:tags)
tags_reflection.chain
# => [<ActiveRecord::Reflection::ThroughReflection: @delegate_reflection=#<ActiveRecord::Reflection::HasManyReflection: @name=:tags...>,
      <ActiveRecord::Reflection::HasManyReflection: @name=:taggings, @options={}, @active_record=Post>]


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1039



def collect_join_chain
  collect_join_reflections [self]
end


  








  

    #collect_join_reflections(seed)   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1196



def collect_join_reflections(seed)
  a = source_reflection.add_as_source seed
  if options[:source_type]
    through_reflection.add_as_polymorphic_through self, a
  else
    through_reflection.add_as_through a
  end
end


  








  

    #constraints  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1170



def constraints
  scope_chain = source_reflection.constraints
  scope_chain << scope if scope
  scope_chain
end


  








  

    #derive_class_name   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1207



def derive_class_name
  # get the class_name of the belongs_to association of the through reflection
  options[:source_type] || source_reflection.class_name
end


  








  

    #inverse_name   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1205



def inverse_name; delegate_reflection.send(:inverse_name); end


  








  

    #join_primary_key(klass = self.klass)  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1083



def join_primary_key(klass = self.klass)
  source_reflection.join_primary_key(klass)
end


  








  

    #join_scopes(table, predicate_builder, klass = self.klass, record = nil)  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1055



def join_scopes(table, predicate_builder, klass = self.klass, record = nil) # :nodoc:
  source_reflection.join_scopes(table, predicate_builder, klass, record) + super
end


  








  

    #klass  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 981



def klass
  @klass ||= delegate_reflection.compute_class(class_name)
end


  








  

    #scopes  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1051



def scopes
  source_reflection.scopes + super
end


  








  

    #source_options  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1122



def source_options
  source_reflection.options
end


  








  

    #source_reflection  
  



  

    

Returns the source of the through reflection. It checks both a singularized and pluralized form for :belongs_to or :has_many.



class Post < ActiveRecord::Base
  has_many :taggings
  has_many :tags, through: :taggings
end

class Tagging < ActiveRecord::Base
  belongs_to :post
  belongs_to :tag
end

tags_reflection = Post.reflect_on_association(:tags)
tags_reflection.source_reflection
# => <ActiveRecord::Reflection::BelongsToReflection: @name=:tag, @active_record=Tagging, @plural_name="tags">


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1002



def source_reflection
  through_reflection.klass._reflect_on_association(source_reflection_name)
end


  








  

    #source_reflection_name  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1102



def source_reflection_name # :nodoc:
  @source_reflection_name ||= begin
    names = [name.to_s.singularize, name].collect(&:to_sym).uniq
    names = names.find_all { |n|
      through_reflection.klass._reflect_on_association(n)
    }

    if names.length > 1
      raise AmbiguousSourceReflectionForThroughAssociation.new(
        active_record.name,
        macro,
        name,
        options,
        source_reflection_names
      )
    end
    names.first
  end
end


  








  

    #source_reflection_names  
  



  

    

Gets an array of possible :through source reflection names in both singular and plural form.



class Post < ActiveRecord::Base
  has_many :taggings
  has_many :tags, through: :taggings
end

tags_reflection = Post.reflect_on_association(:tags)
tags_reflection.source_reflection_names
# => [:tag, :tags]


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1098



def source_reflection_names
  options[:source] ? [options[:source]] : [name.to_s.singularize, name].uniq
end


  








  

    #through_options  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1126



def through_options
  through_reflection.options
end


  








  

    #through_reflection   (readonly)
  



  

    

Returns the AssociationReflection object specified in the :through option of a HasManyThrough or HasOneThrough association.



class Post < ActiveRecord::Base
  has_many :taggings
  has_many :tags, through: :taggings
end

tags_reflection = Post.reflect_on_association(:tags)
tags_reflection.through_reflection
# => <ActiveRecord::Reflection::HasManyReflection: @name=:taggings, @active_record=Post, @plural_name="taggings">


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/reflection.rb', line 1018



def through_reflection
  active_record._reflect_on_association(options[:through])
end